1. Related Technical Fields
Related technical fields travel guidance devices, travel guidance methods, and computer programs which perform guidance of vehicle-related travel.
2. Related Art
Recently, navigation devices that perform vehicle travel guidance so that a driver can reach a desired destination easily are often installed in vehicles. Here, a navigation device is a device which is capable of detecting the current position of a vehicle using a GPS receiver or the like, obtaining map data corresponding to the current position from a recording medium such as a DVD-ROM or an HDD, and displaying the obtained map data on a liquid crystal monitor. The map data including the current position of the vehicle are read from the recording medium or the like, and on the basis of the map data, a map image of the periphery of the current vehicle position is drawn and displayed on a display device. At the same time, a vehicle position mark is superposed on the map image, and as the vehicle moves, the map image is scrolled, or the map image is fixed on the screen and the vehicle position mark is moved. Thus, the current location of the moving vehicle can be learned at a glance. The navigation device above includes a route search function that, when a desired destination is set, searches for an optimal route from a departure point (e.g., the current vehicle position) to the set destination, and further includes a travel guidance function that provides guidance for traveling along the route found. In recent years, mobile telephones, personal digital assistants (PDAs), personal computers and the like often have functions similar to the navigation device above.
Moreover, when the navigation device and the like above perform vehicle travel guidance, such guidance takes into account a zone where the vehicle is prohibited from changing lanes (hereinafter referred to as a “no-lane-change zone”). For example, according to art described in Japanese Patent Application Publication No. JP-A-2007-127416 (pages 8 to 11, FIG. 2), a position of a guidance target point for providing guidance, such as turning right or left at a guided intersection, is offset toward a near side by a distance that corresponds to the length of a no-lane-change zone if there is a no-lane-change zone between the guidance target point and the guided intersection.